Like it or not, someone other than your doctor is in the business of recommending your medical treatments.

That job falls to a little-known group called the U.S. Preventive Services Task Force. It has been the subject of increasing controversy, not because it guides decisions but because some of its recommendations have shifted from encouraging expensive and expansive screening to discouraging its overuse. As with many things in medicine, it’s much more popular to do stuff than to tell people “no.”

Created in 1984 by Congress, the task force makes recommendations about clinical services, like screening for common diseases, that are essential elements of preventive care. The panel of volunteers is appointed by a federal government agency and is composed of experts in a wide field of primary care and preventive medicine, including pediatrics, family medicine and internal medicine, as well as obstetrics and gynecology, nursing and behavioral health.

Their job is to come up with the evidence that justifies one service and not another, whether the problem involves children’s cavities or cancer. What they decide makes a difference in whether doctors routinely think to order a prostate test, a mammogram or a screen for autism.

The panel makes a recommendation and issues a specific letter grade to a service or procedure. An “A” means that the task force recommends that all clinicians offer or provide a service, like screening, because there is a high certainty of a substantial net benefit. A “B” also means that all clinicians should offer or provide a service, but that there is only a high certainty of a moderate net benefit.

A “C” level recommendation tells doctors that a service should not be universally offered. Instead, it should be left to the individual patient and clinician to decide. A “D” recommendation signals that a service should not be used because there is at least a moderate certainty of no net benefits or that harms outweigh benefits.

The Affordable Care Act, in an effort to encourage the use of evidence-based, beneficial preventive services, mandates that all recommendations with an “A” or “B” rating be covered by insurance with no out-of-pocket payments. In other words, the services have to be completely free, regardless of the type or level of insurance coverage.

This doesn’t, however, mean that recommendations with a “C” or “D” won’t be covered by insurance. They almost always are. They just might be subject to deductibles, co-pays or coinsurance. It’s up to the insurance provider to decide.

A final grade, that of “I,” signifies that there is insufficient evidence for a complete assessment of the harms and benefits. It’s a call for more research, as was done recently for autism screening.

As I’ve discussed in the past, mammography screening for women 50 to 74 years earned a “B” recommendation, as there is a moderate net benefit to its universal biennial use. However, a “C” recommendation for those younger than 50 indicates that women and their doctors should make the decision after weighing the personal risks and benefits.

The “D” given to screening for prostate cancer with a PSA test for prostate cancer argues that the use of this test most likely does more harm than good. The task force’s review concluded that PSA screening does not result in a decrease in mortality when used broadly and that the extra treatment screening induces has caused significant problems, including the occasional death.

This type of recommendation has consequences. The use of PSA screening in men has fallen. A recent study published in The Journal of the American Medical Association showed that in 2010, before the government task force’s “D” announcement, about 35 percent of men between 50 and 74 were screened versus just over 30 percent in 2013.

Another study in the same journal examined the incidence of prostate cancer and the stage of cancer being diagnosed before and after the latest recommendations. In 2008, about 541 cases of prostate cancer were diagnosed per 100,000 men. In 2012, that number had dropped to 416. From just 2011 to 2012, the researchers estimated that roughly 33,000 fewer cases of prostate cancer had been diagnosed nationwide.

Is that good or bad? It’s hard to say. Certainly, some of those nondiagnoses will never cause problems and not lead to death. But some might. In an accompanying editorial, Dr. David Penson, chairman of urology at Vanderbilt University Medical Center, argued that better strategies might be needed. Perhaps we could screen less often, or target those at highest risk. We might even raise the PSA threshold of suspicion, so that fewer nonthreatening cases of cancer are acted upon.

The recommendations on mammograms, while less restrictive, have caused even more controversy. However, they haven’t really gone into effect. In 2009, when the task force issued the “C” rating for women younger than 50, many people were upset. Amendments to the Affordable Care Act specifically mandated that the law would consider the 2002 report’s “B” rating, and not the 2009 report’s “C,” when making coverage decisions.

In other words, Obamacare specifically ignored the 2009 recommendation, and has continued to do so, until the next set of recommendations comes in. That’s happening now, and once again, it’s leading to controversy. Bills have been submitted in both the House and the Senate to continue to override the task force. Another bill would radically change how the task force works and functions.

It’s hard not to read this as an attack on the task force itself. Some argue that the group is taking away medical procedures that could save lives.

That’s just not the case. Congress, in passing the Affordable Care Act, always intended that recommendations from the task force, along with other bodies like the Advisory Committee on Immunization Practices, Bright Futures and the Committee on Women’s Clinical Preventive Services, be a floor, not a ceiling. They were just supposed to identify those services that were so beneficial that they should be free for anyone.

When the task force doesn’t give an “A” or “B,” all it’s doing is leaving it to payers to decide whether services should be covered or free. That’s how insurance works for almost all other medical services. There’s no reason to blame the group for that.

Further, if lawmakers don’t like what payers are doing, they can overrule them with legislation, just as they have done for screening mammograms.

That may make many people uncomfortable. After all, it’s hard to argue that politicians have the necessary expertise to understand the risks and benefits of complex medical procedures and tests. Unfortunately, insurance companies are obviously conflicted in determining what to cover, and many Americans aren’t happy leaving such decisions in their hands, either. If we expect individuals to negotiate for packages designed just for them with respect to what kind of screening is covered, we will be back to the individually rated and broken insurance system that we had before the Affordable Care Act went into effect.

If we don’t want to leave things up to lawmakers or insurance companies, one of the few options left is to identify non-conflicted experts and let them make recommendations. As we’ve seen from recent events, Americans aren’t always satisfied with that either.

Someone has to decide.

© 2015 The New York Times Company